WO1994021088A2 - Signaux a codage optique - Google Patents

Signaux a codage optique Download PDF

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Publication number
WO1994021088A2
WO1994021088A2 PCT/GB1994/000397 GB9400397W WO9421088A2 WO 1994021088 A2 WO1994021088 A2 WO 1994021088A2 GB 9400397 W GB9400397 W GB 9400397W WO 9421088 A2 WO9421088 A2 WO 9421088A2
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WO
WIPO (PCT)
Prior art keywords
word
optical
bit
target
pulse
Prior art date
Application number
PCT/GB1994/000397
Other languages
English (en)
Other versions
WO1994021088A3 (fr
Inventor
David Cotter
Original Assignee
British Telecommunications Public Limited Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB939318799A external-priority patent/GB9318799D0/en
Priority to EP94907651A priority Critical patent/EP0687370B1/fr
Priority to AU61140/94A priority patent/AU690097B2/en
Priority to CA002157492A priority patent/CA2157492C/fr
Priority to US08/530,268 priority patent/US5900956A/en
Priority to JP51970494A priority patent/JP3512800B2/ja
Priority to KR1019950703737A priority patent/KR100321073B1/ko
Priority to DE69404130T priority patent/DE69404130T2/de
Application filed by British Telecommunications Public Limited Company filed Critical British Telecommunications Public Limited Company
Publication of WO1994021088A2 publication Critical patent/WO1994021088A2/fr
Publication of WO1994021088A3 publication Critical patent/WO1994021088A3/fr
Priority to EP95909871A priority patent/EP0783725B1/fr
Priority to DE1995633650 priority patent/DE69533650D1/de
Priority to CA002183347A priority patent/CA2183347C/fr
Priority to KR1019960704890A priority patent/KR100363311B1/ko
Priority to JP7522754A priority patent/JPH09512642A/ja
Priority to PCT/GB1995/000425 priority patent/WO1995023997A1/fr
Priority to HK97102524A priority patent/HK1001009A1/xx

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0003—Details
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06E—OPTICAL COMPUTING DEVICES; COMPUTING DEVICES USING OTHER RADIATIONS WITH SIMILAR PROPERTIES
    • G06E1/00—Devices for processing exclusively digital data
    • G06E1/02—Devices for processing exclusively digital data operating upon the order or content of the data handled
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q11/0066—Provisions for optical burst or packet networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0007—Construction
    • H04Q2011/0009—Construction using wavelength filters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0007—Construction
    • H04Q2011/0013—Construction using gating amplifiers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0007—Construction
    • H04Q2011/0015—Construction using splitting combining
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0007—Construction
    • H04Q2011/002—Construction using optical delay lines or optical buffers or optical recirculation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0007—Construction
    • H04Q2011/0035—Construction using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0005—Switch and router aspects
    • H04Q2011/0037—Operation
    • H04Q2011/0041—Optical control

Definitions

  • the present invention relates to a method and apparatus for processing optically encoded signals, and in particular to the recognition of an optically encoded binary word.
  • &®r ⁇ if W ⁇ T is true, where T is the target word and W is the word to be compared.
  • W®T is the operation -
  • the present inventor has realised that with an appropriate choice of codewords it is possible to carry out recognition entirely in the optical domain, using an optical AND operation.
  • the preferred embodiment restricts the encoding words to a sub-set of all the possible n-bit binary words and then carries out word recognition using a method based entirely on AND operations at the bit level.
  • the AND operation as represented by the simple scalar product of two optical fields, is a fundamental capability of many non-linear optical devices. Accordingly, it can be implemented far more straightforwardly than other logical operations, such as the exclusive-OR operation previously used for optical code word recognition. This approach will therefore allow the processing of optical code words at ultrafast speeds far beyond the capability of electronic logic circuitry, but with the possibility of modest energy requirements, high stability and low latency in the signal processing devices, together with small physical volume and potential for integration.
  • bit rate is not limited by the response time of the photodetector and electronics. This means that when, for example, the system is used to read the header in a very high speed optical packet, this can be done at the full bit rate of the packet.
  • this process of recognition may be carried out at a switching node in which an incoming packet encoded in RTZ format, e.g. as solitons, is routed according to whether the packet address field H is equal to a local address A.
  • a single optical pulse P which is in precise synchronism with the incoming packet may be generated and passed through a passive split-delay-recombine network which converts it to a pulse train representing A (the binary logical complement of the local address A) .
  • the incoming packet header H and the pulse train A are, in this example, incident simultaneously at an ultra fast optical AND gate.
  • the output of the gate is zero only if H equals A. If H is not equal to A, then at least one optical pulse is obtained at the output of the optical AND gate. This output is detected (i.e. converted to the electrical domain) and may be used to control the routing switch. Only one optical AND gate is needed. No electrical summation or multi-level discrimination is needed. Since the output of the gate is immediately converted to the electrical domain, the gate need not be wavelength preserving, neither need it have high optical efficiency nor need it be cascadable. Any ultrafast non linear optical device yielding an output proportional to the scalar product of two input fields may be used.
  • the non-linear optical device used to carry out the AND operation may, for example, be a SHG (second harmonic generator) crystal.
  • SHG second harmonic generator
  • other non-linear optical processes may be used, such as optical sum- frequency or difference-frequency mixing, harmonic generation, polarisation rotation using the optical Kerr effect, cross-phase modulation, degenerate four-wave mixing, or optical phase conjugation. All these non-linear optical phenomena produce an output proportional to the scalar product of two input optical signals.
  • a variety of non-linear optical media may be used, such as crystals, semiconductors, organic materials or glasses. It may be particularly advantageous to use a non-linear optical medium in the form of an optical waveguide.
  • the present invention is not limited to processing signals representing a time-series, such as the header of a packet on an optical network. It may also be used for pattern or image recognition, in which case the different bits of the binary word will be distributed in space rather than in time.
  • the different bits W 1f W 2 ...W j of the word then correspond to binary pixels, and the image is recognised by carrying out AND operations on the pixels in the optical domain with the complement of the binary target image.
  • the code word W is provided with a datum pulse having a fixed, bit-asynchronous time relationship to the rest of the word, and the datum pulse is used in generating a pulse sequence T' dependent on the target word T.
  • the word T' is generated by applying the word W including the datum pulse to a splitter/delay network, the different arms of the network having different respective delays determined depending upon the target word T.
  • This aspect of the present invention overcomes the need to generate locally a pulse synchronised to the incoming code word. Instead, each code word is provided with an additional pulse which has a fixed time relationship to the code word pulse train but is bit- asynchronous with it. For example, the datum pulse may occur 1.5 bit periods before the start of the header of a packet. This datum pulse is then used in generating a word related to the target word T for ANDing with the incoming code word. This may be done, for example, using a network which creates a signal including the logical complement T of the target word.
  • an address reader for detecting and recognising the address associated with a packet carried on an optical communication system, characterised in that the said means are arranged to recognise the address by a method in accordance with the first aspect of the present invention.
  • Figure 1 is a diagram illustrating the number of words in the restricted word set used in the present invention
  • Figures 2a and 2b are schematics of an optical communication system embodying the invention, and a word- forming network;
  • Figure 3 shows an optical AND gate
  • Figures 4a and 4b illustrate the use of the system of Figure 2 in recognising a header address field
  • Figure 5 is a schematic of an alternative embodiment of the present invention
  • Figure 6 is a more detailed view of the passive network of Figure 5;
  • Figures 7a to 7e are timing diagrams illustrating the operation of the network of Figure 6;
  • Figure 8 is a further example of an optical AND gate
  • Figure 9 is a further alternative embodiment of the AND gate
  • Figure 10 is a schematic of an alternative embodiment using a configurable word-forming network
  • Figure 11(a) is a schematic of a further embodiment configurable to select different header fields and Figure 1Kb) shows the different header fields;
  • Figure 12 is a schematic of a further alternative embodiment.
  • a broadband optical network carries packets of optically encoded data.
  • the packets of data are directed to one or other of two branches of the network. Upstream of the switch 2, part of the signal carried on the network is diverted and gated so that the header of a packet of traffic data is fed to a pulse- coincidence detection gate 3.
  • the binary word W forming the address is compared with the complement of a target word T supplied to the gate from a word-forming network 3.
  • the input to the word-forming network 3 is provided by a clock-recovery unit CR.
  • the output of the gate 3 is converted to an electrical signal by a detector 5 and the resulting signal used to control the switch 2.
  • a buffer 1 delays the arrival of the packet at the routing switch 2 until the routing switch has been set correctly.
  • the gate 3 carries out a bit-wise Boolean AND operation on the pulse train.
  • the gate may consist of a suitable non-linear crystal, oriented in such a way that the two optical pulse trains give rise to efficient generation of second harmonic radiation only if two input pulses A and B are incident simultaneously at the crystal and intersect in the crystal at different angles. This is a technique known as non-collinear SHG (second harmonic generation) .
  • the crystal orientation satisfies the phase matching condition that ensures no significant SHG occurs with a single pulse on its own.
  • the second harmonic output from the crystal is detected and used to control the electro-optic switch 2 to give the correct routing for the packet.
  • the routing switch could be, for example, a planar waveguide lithium niobate 2x2 switch with sub-nanosecond switching time, such as is manufactured by E-Tek Dynamics and supplied by Optilas Limited of Milton Keynes.
  • the photodetector converts the optical .AND signal into an electrical signal.
  • An aperture and filter prevent the optical signals input to the crystal from reaching the photodetector, but allow the SHG signal to pass.
  • an electronic discriminator may be placed after the photodetector to set a decision threshold level so that the output is one when A and B inputs are present simultaneously.
  • Type II phase matching second harmonic generation may be used.
  • the two input beams are collinear but their electrical field vectors are polarised in orthogonal directions.
  • the crystal is then oriented so that SHG is obtained only when input pulses are present simultaneously in each of two polarisation directions.
  • a spectral filter blocks the input beams before they reach the photodetector.
  • a clock recovery unit generates an optical clock pulse in exact synchronism with the incoming optical packets (i.e. 1 pulse per packet) .
  • This clock recovery may be done using an optical phase locked loop of the type described by S P Dijaili et al [8] .
  • the clock pulse is then passed through a passive optical network that converts the single pulse into a pulse train that represents a binary word.
  • This word-forming network may comprise a multi-wave splitter and recombiner between which are a number of separate optical paths. The lengths of these paths are all slightly different and chosen so that the output pulse train represents the logical complement of the target word T.
  • the word-forming network is thus "hard-wired" to produce the required word T.
  • This type of passive network may conveniently be fabricated using photolithographic processing together with planar silica waveguide technology (as described for example by C J Beaumont et al [9] ) .
  • the optical delay line shown in the Figure delays the incoming packet until there has been sufficient time for the electro-optic switch to be set correctly.
  • the word-forming network may be flexibly configured, for example under network management control. This is of particular use where it is required to change the address of a node or to reconfigure a communications network dynamically, for example in response to a change in traffic demands, or in response to a network fault condition.
  • the word-forming network consists of a number of optical paths which can be selected by means of electro-optic or opto-mechanical switches - some or all of the optical paths may contain such a switch. By means of electrical signals applied to these switches, so as to block some paths and unblock or reconfigure others, it is possible to reconfigure the word-forming network in a variety of ways so as in effect to change at will the output word T.
  • Figure 10 shows a first example of such an approach.
  • a number k of fixed word-forming networks are provided, and a given one of the networks is chosen using 1 x k switches.
  • Each of the different networks corresponds to a different target word.
  • Figure 11 (a) shows an alternative arrangement where it is possible to perform the word-recognition process on different fields of the header ( Figure 1Kb)) .
  • the word-forming network N (which may be fixed or re- configurable) is used to recognise whether the input word matches a target word T, which in this case is the same length as the sub-divided fields of the header.
  • T the target word
  • Figure 12 shows a further alternative embodiment offering even greater flexibility.
  • both the target word and also the header field if required can be freely selected by using the switches to configure fully both the target word and the second input to the optical -AND gate.
  • the word-forming network acts on a datum pulse carried with the word to be recognised, in the manner described in further detail below with respect to Figure 5.
  • Configurable word forming networks may also be used similarly with independently generated synchronised pulses in circuit configurations as described, for example, with reference to Figure 2A.
  • Figure 5 shows an alternative embodiment which overcomes the need for a locally generated synchronising pulse P in generating the target word.
  • the incoming packet is split, with one branch going via a buffer 1 to the routing switch 2 and the other branch being used to provide an input to the AND gate 3.
  • the manner in which the other input to the .AND gate is generated is modified.
  • the incoming packet now includes an additional pulse, the "datum pulse" which precedes the header and has a fixed time relationship to the header pulse train.
  • the datum pulse is bit-asynchronous in relation to the header, i.e. it is not separated from the header by an integral number of bit periods. In the presently described example, the datum pulse occurs 1.5 bit periods before the start of the header.
  • the incoming packet is split a second time, with one branch being applied to a passive network 4' and the other branch going directly to the input of the optical AND gate 3.
  • the network 4' which is shown in further detail in Figure 6, has n arms, where n is the total number of zeros in A.
  • the network reproduces and recombines the entire packet including the datum pulse n times, each version being delayed by a time T-, which is the time difference between the datum pulse and the jth zero in the local address A.
  • T- is the time difference between the datum pulse and the jth zero in the local address A.
  • the output from the network 4' is applied to the AND gate 3 and as before the output from the AND gate 3 is non ⁇ zero if H is not equal to A.
  • This technique therefore allows self-routing to occur without the need for bit-level synchronisation at the network node.
  • the passive network 4' can be fabricated using compact planar silica-on-silicon technology, providing a component which can readily be exchanged, for example, to allow a change of the local address.
  • the bit period is T and the datum pulse occurs 1.5T before the first bit of the header field H.
  • This packet is input to a passive network N with delays to produce the two delayed packets shown in Figures 7 (b) and (c) which are combined to produce the optical signal shown in Figure 7 (d) .
  • This signal is applied to one input of the optical AND gate, whilst the other input to the gate is the undelayed packet shown in Figure 7 (e) .
  • the width of each optical pulse in the packet is substantially shorter than the bit period r.
  • the exact amount by which the pulses must be shorter than T depends on factors such as the efficiency of the AND gate, the photo-detector sensitivity, the temporal shape of the pulses, and the optical and electrical noise levels. In practice this should be determined by trial and error; however the following approximate criteria give a guide. For rectangular optical pulses of width t, we require t ⁇ T/2 . For pulses with a temporal shape that is sech in intensity (such as soliton pulses) , we require t ⁇ T/4 approximately, where t is the full width at half-maximum intensity of the pulse.
  • the optical wavelength is 1.55 microns
  • the individual optical pulses are 2ps wide.
  • the AND gate can have a non ⁇ zero output only if the datum pulses that are delayed by the passive network N (and so occur in the signal Figure 5(d) applied to one input of the AND gate) coincide with pulses in the header address field of the non-delayed signal Figure 7(e) which is applied to the other input of the AND gate. This results from the arrangement of the datum pulse so that it is out of synchronism with the rest of the packet, and the use of delays T- in the passive network N that are non-integer multiples of the bit period T.
  • the two splitters are standard fused fibre couplers.
  • the splitter ratios are not particularly critical.
  • the first splitter could perhaps have a ratio of 10:90% so that most of the energy in the incoming packet is transferred through the routing switch whilst a smaller fraction is passed to the header recognition part of the circuit.
  • the second splitter (the one just before the passive network N) could have a splitting ratio chosen so that the intensities of individual pulses at the two inputs to the optical .AND gate are roughly equal.
  • the buffer may conveniently be a length of monomode optical fibre - sufficiently long so that the packet is delayed such that the state of the routing switch has been set correctly before the packet arrives at the switch. In this case "sufficient" might be -2 ns delay, which would be provided by about 40 cm of fibre.
  • the passive device N may conveniently be fabricated using photolithographic processing together with planar silica waveguide technology (as is described for example by CJ Beaumont et al in BT Technology Journal Vol. 9, No 4, Pages 30-35, October 1991) .
  • the O/E convertor may conveniently be a photomultiplier tube followed by a TTL monostable circuit with an output pulse width just long enough to hold the routing switch in the "activated" state following an electrical output pulse from the photomultiplier tube to allow the complete packet to pass through (for example, a 500 bit packet at 100 Gbit/s would need the switch to be held in the correct state for at least 5 ns) .
  • the nonlinear optical device used to carry out the optical .AND operation may, for example, be a second- harmonic generation crystal, although many other nonlinear optical processes may be used.
  • the other components described above are instanced by way of example only. As will be apparent, many alternative device types may be substituted in implementing the invention.
  • FIG. 8 One example of an appropriate optical AND gate and detector is shown in Figure 8.
  • the system is contained in a lightproof housing 60.
  • the lens 61 brings the output from the two input fibres a, b to the same focal spot inside on SHG crystal 62.
  • a fraction of the input light is converted to the second harmonic wavelength.
  • the crystal is oriented in such a way that a second-harmonic pulse is produced only if a pulse from each of the two fibres is incident simultaneously at the crystal; if a pulse from one of the input fibres reaches the crystal, without simultaneously a pulse from the other fibre, there is no second-harmonic pulse generated.
  • This is a well-known technique known as 'non-collinear phase-matching' .
  • the purpose of the aperture 63 and filter 64 is to prevent light from the input fibres reaching the photomultiplier, whilst allowing the second-harmonic beam to pass.
  • the filter should have a spectral characteristic that attenuates the input wavelength (1.55 ⁇ m) strongly and attenuates the second-harmonic (0.77 ⁇ m) to a much lesser degree.
  • a suitable filter would be the glass type KG5 manufactured by Schott Glastechnike.
  • the output from the filter passes to a photomultiplier 65.
  • Figure 9 shows an alternative AND gate using four-wave mixing in a semiconductor laser amplifier (SLA) .
  • SLA semiconductor laser amplifier
  • two signals (A and B) at wavelength ⁇ s are injected into the SLA in orthogonal polarisation states.
  • a CW pump beam P at ⁇ p copolarised with signal A is also injected into the SLA.
  • Four-wave mixing occurs between signal A and P to produce primary side-bands at ⁇ s - ( ⁇ p - ⁇ s ) and ⁇ +( ⁇ - ⁇ s ) .
  • a gain modulation (and hence refractive index modulation) is impressed on the SLA at the beat frequency between ⁇ and ⁇ -.
  • the signal B sees this modulation and produces side-bands at ⁇ s +( ⁇ - ⁇ s ) and ⁇ s - ( ⁇ p - ⁇ s ) in the orthogonal polarisation state to signals A and P. Mixing does not occur when the pump beam P and signal beam are injected into the SLA orthogonally polarised, so no wavelength conversion of B occurs unless A is also present.
  • the signal at ⁇ 8 - ( ⁇ p - ⁇ s ) in the B polarisation plane is isolated through the use of an optical polariser and bandpass filter. This signal represents an .AND between signal A and signal B, as the P beam is on continuously.
  • signal A at 1553.15nm is combined with a pump P at 1555.08nm from a tunable external cavity laser 91 in a 3dB coupler.
  • the combined signal A + P is amplified in an erbium-doped fibre amplifier 92 and passes through a beam splitter/combiner 93 and is combined in an orthogonal polarisation state with A + P.
  • the polarisations of A, B and P are optimised for maximum transmission using the fibre pigtailed polarisation beam splitter/combiner.
  • the three signals are then coupled into a 500 ⁇ m long strained-layer 8-well MQW buried heterostructure SLA with a gain peak at -1.56 ⁇ m when biased at 340mA.
  • the output from the SLA passes through a fibre polariser adjusted to extinguish the signals in the A + P polarisation axis. This is followed by a 0.6nm fibre- grating band pass filter centred at 1551.20nm to isolate the AND signal. This signal is further amplified before being detected on a high-speed photodetector (bandwidth ⁇ -18GHz) .
  • the output from the photodetector may be used, for example, to control a routing switch. For demonstration purposes the output may be viewed on a oscilloscope.
  • the circuit of Figure 9 shows the inputs A and B generated using a pulse- pattern generator based on a Mach-Zehnder modulator
  • the AND gate may take, for example, the word to be recognised W as input A, and the output of the word- forming network, corresponding to the complement of the target word T, as the input B.
  • An essential operation in information processing is to recognise binary words (such as, for example, the header address sequences in a packet-switched telecommunications network) .
  • the task is to determine whether
  • the present invention uses an alternative approach to word recognition using an algorithm based on AND operations at the bit level. Unlike other logic operations, the AND operation, as represented by the simple scalar product of two optical fields, is fundamental to all ultrafast nonlinear optical phenomena [6] .
  • the algorithm therefore opens up many new device possibilities having desirable properties such as low latency (short delay time between input and output signals) , passive long-term stability, small physical volume and potential for integration.
  • W be an n-bit word containing p ones (p ⁇ q) which is added to S q .
  • W is defined as before except that p > q, we may choose from the original set S a word W having n - p zeros in the positions corresponding to the zeros in W , and p - q zeros in any other positions.
  • Figure 1 shows the word length n that is needed, depending on the total number of words required, when using the restricted word set (S n/2 for n even or S (r . 1)/2 for n odd) or unrestricted coding (2 n -l) .

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Communication System (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Holo Graphy (AREA)
  • Signal Processing For Digital Recording And Reproducing (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

Dans une méthode de reconnaissance d'un mot binaire à codage optique, le mot est choisi parmi un sous-ensemble de mots binaires pour lesquels WOT=0 si W=T, WOT=1 si W¸T est vrai, où T est le mot cible, W est le mot à comparer et O est l'opération indiquée par (I). Le mot est reconnu par une opération ET booléenne dans le domaine optique au niveau du bit. L'opération est effectuée sur le mot à reconnaître et sur le complément du mot cible. On peut effectuer l'opération ET en introduisant le mot a reconnaître et le mot cible dans un cristal non linéaire et en détectant la deuxième sortie harmonique du cristal. Le complément du mot cible peut être générée par un réseau fixe d'élaboration de mots. La méthode peut être appliquée à la reconnaissance de l'adresse d'un paquet dans un réseau optique.
PCT/GB1994/000397 1993-03-02 1994-03-01 Signaux a codage optique WO1994021088A2 (fr)

Priority Applications (14)

Application Number Priority Date Filing Date Title
EP94907651A EP0687370B1 (fr) 1993-03-02 1994-03-01 Procede a et appareil pour identifier des signaux a codage optique
AU61140/94A AU690097B2 (en) 1993-03-02 1994-03-01 Optically encoded signals
CA002157492A CA2157492C (fr) 1993-03-02 1994-03-01 Signaux a codage optique
US08/530,268 US5900956A (en) 1993-03-02 1994-03-01 Optically encoded signals
JP51970494A JP3512800B2 (ja) 1993-03-02 1994-03-01 光学的にエンコードされた信号
KR1019950703737A KR100321073B1 (ko) 1993-03-02 1994-03-01 광학적으로부호화된신호를처리하는방법및장치
DE69404130T DE69404130T2 (de) 1993-03-02 1994-03-01 Verfahren und vorrichtung zur erkennung von optisch kodierten signalen
EP95909871A EP0783725B1 (fr) 1994-03-01 1995-02-03 Poste optique "et"
DE1995633650 DE69533650D1 (de) 1994-03-01 1995-02-03 Optisches "und" gatter
PCT/GB1995/000425 WO1995023997A1 (fr) 1994-03-01 1995-02-28 Porte optique et
JP7522754A JPH09512642A (ja) 1994-03-01 1995-02-28 光アンドゲート
CA002183347A CA2183347C (fr) 1994-03-01 1995-02-28 Porte optique et
KR1019960704890A KR100363311B1 (ko) 1994-03-01 1995-02-28 And논리연산을수행하는광학and게이트
HK97102524A HK1001009A1 (en) 1993-03-02 1997-12-19 Method of and device for recognizing optically encoded signals

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP93301568 1993-03-02
EP93301568.7 1993-03-02
GB9318799.5 1993-09-10
GB939318799A GB9318799D0 (en) 1993-09-10 1993-09-10 Optical codeword recognition

Publications (2)

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995023997A1 (fr) * 1994-03-01 1995-09-08 British Telecommunications Public Limited Company Porte optique et
WO1995032568A1 (fr) * 1994-05-23 1995-11-30 British Telecommunications Public Limited Company Traitement optique de paquets
NL1000682C2 (nl) * 1995-05-09 1996-11-12 Nederland Ptt Signaal Processor.
WO1999014649A2 (fr) * 1997-09-18 1999-03-25 British Telecommunications Public Limited Company Procede servant a obtenir un train de signaux optiques
US6327154B1 (en) 1998-11-06 2001-12-04 Sierra Wireless, Inc. Battery case for PCMCIA card modem with antenna
WO2007068914A1 (fr) * 2005-12-12 2007-06-21 Qinetiq Limited Correlateur
WO2008110214A1 (fr) * 2007-03-15 2008-09-18 Telefonaktiebolaget Lm Ericsson (Publ) Nœud de communications et procédé de routage de signaux par paquets de données optiques
WO2009015689A1 (fr) * 2007-07-31 2009-02-05 Telefonaktiebolaget Lm Ericsson (Publ) Commutateur batcher banyan tout optique, commutateur batcher, commutateur banyan et gestionnaire de contention

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5999287A (en) * 1994-12-23 1999-12-07 British Telecommunications Public Limited Company Node in optical TDM network
WO1998044641A2 (fr) 1997-02-14 1998-10-08 Massachusetts Institute Of Technology Convetisseur de debit binaire optique
US6175433B1 (en) * 1997-06-17 2001-01-16 Massachusetts Institute Of Technology Optical bit rate converter
GB9712020D0 (en) * 1997-06-09 1997-08-06 Northern Telecom Ltd Equalisation, pulse shaping and regeneration of optical signals
EP1139587B1 (fr) * 2000-03-27 2006-10-18 BRITISH TELECOMMUNICATIONS public limited company Méthode et dispositif pour mesurer la gigue temporelle d'un signal optique
US6515792B1 (en) * 2000-04-12 2003-02-04 Massachusetts Institute Of Technology Fast optical wavelength shifter
US6810407B1 (en) 2000-07-14 2004-10-26 Lucent Technologies Inc. Optical boolean logic devices for data encryption
AU2002223987A1 (en) * 2000-11-08 2002-05-21 Al J. C. Baur System and method for improving network router efficiency and alleviating network bottlenecks and overloads
US20030128987A1 (en) * 2000-11-08 2003-07-10 Yaron Mayer System and method for improving the efficiency of routers on the internet and/or cellular networks an/or other networks and alleviating bottlenecks and overloads on the network
US6504612B2 (en) 2000-11-14 2003-01-07 Georgia Tech Research Corporation Electromagnetic wave analyzer
US6636337B2 (en) * 2001-02-09 2003-10-21 Nortel Networks Limited Optical switching device based on stable, non-absorbing optical hard limiters
US6649476B2 (en) * 2001-02-15 2003-11-18 Micron Technology, Inc. Monotonic dynamic-static pseudo-NMOS logic circuit and method of forming a logic gate array
US6603904B1 (en) 2001-03-28 2003-08-05 Jaffalight Holdings Llc All optical narrow pulse generator and switch for dense time division multiplexing and code division multiplexing
GB2378553B (en) * 2001-08-08 2004-11-10 Corning Ltd Bit Differential Processing
AU2002366987A1 (en) * 2001-12-28 2003-07-30 Al Baur System and method for improving network router efficiency and alleviating network bottlenecks and overloads

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62232625A (ja) * 1986-04-02 1987-10-13 Nec Corp 光デイジタル信号一致検出回路
US4918635A (en) * 1988-11-15 1990-04-17 Yao Li Ultrafast digital photonic signal processing using optical noncollinear second harmonic generation
WO1991018485A1 (fr) * 1990-05-23 1991-11-28 Ascom Tech Ag Unite de reconnaissance de mots de code et son utilisation

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4519046A (en) * 1979-12-09 1985-05-21 Cole Trevor W Signal processing apparatus and method
JPH07114409B2 (ja) * 1988-06-29 1995-12-06 松下電器産業株式会社 ループ状データ伝送装置
US5060305A (en) * 1989-08-29 1991-10-22 The Trustees Of Princeton University Self clocked, self routed photonic switch
US5239399A (en) * 1991-08-22 1993-08-24 Radiant Technologies Electrical-optical interface device
GB9200897D0 (en) * 1992-01-16 1992-03-11 British Telecomm Optical processing in asynchronous transfer mode network
IT1272079B (it) * 1993-12-16 1997-06-11 Cselt Centro Studi Lab Telecom Procedimento e dispositivo per la sincronizzazione fine di celle atm in nodi atm ottici

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62232625A (ja) * 1986-04-02 1987-10-13 Nec Corp 光デイジタル信号一致検出回路
US4918635A (en) * 1988-11-15 1990-04-17 Yao Li Ultrafast digital photonic signal processing using optical noncollinear second harmonic generation
WO1991018485A1 (fr) * 1990-05-23 1991-11-28 Ascom Tech Ag Unite de reconnaissance de mots de code et son utilisation

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
COMPUTER COMMUNICATIONS, vol.16, no.1, January 1993, GUILDFORD GB pages 54 - 61, XP337058 LOCATI ET AL 'Study of all optical Metropolitan Area Networks' *
OPTICAL ENGINEERING, vol.29, no.3, March 1990, BELLINGHAM US pages 170 - 182, XP113511 PRUCNAL ET AL 'Self-routing photonic switching with optically processed control' *
PATENT ABSTRACTS OF JAPAN vol. 12, no. 100 (P-683) (2947) 2 April 1988 & JP,A,62 232 625 (NEC) 13 October 1987 *
See also references of EP0687370A1 *

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995023997A1 (fr) * 1994-03-01 1995-09-08 British Telecommunications Public Limited Company Porte optique et
WO1995032568A1 (fr) * 1994-05-23 1995-11-30 British Telecommunications Public Limited Company Traitement optique de paquets
AU696534B2 (en) * 1994-05-23 1998-09-10 British Telecommunications Public Limited Company Optical packet processing
US5831752A (en) * 1994-05-23 1998-11-03 British Telecommunications Public Limited Company Optical packet processing
NL1000682C2 (nl) * 1995-05-09 1996-11-12 Nederland Ptt Signaal Processor.
EP0742660A1 (fr) * 1995-05-09 1996-11-13 Koninklijke KPN N.V. Processeur à signaux à conversion de données
US6452704B1 (en) 1997-09-18 2002-09-17 British Telecommunications Public Limited Company Method of obtaining an optical signal stream
WO1999014649A2 (fr) * 1997-09-18 1999-03-25 British Telecommunications Public Limited Company Procede servant a obtenir un train de signaux optiques
WO1999014649A3 (fr) * 1997-09-18 1999-12-09 British Telecomm Procede servant a obtenir un train de signaux optiques
US6327154B1 (en) 1998-11-06 2001-12-04 Sierra Wireless, Inc. Battery case for PCMCIA card modem with antenna
WO2007068914A1 (fr) * 2005-12-12 2007-06-21 Qinetiq Limited Correlateur
US8145011B2 (en) 2005-12-12 2012-03-27 Qinetiq Limited Correlation apparatus
WO2008110214A1 (fr) * 2007-03-15 2008-09-18 Telefonaktiebolaget Lm Ericsson (Publ) Nœud de communications et procédé de routage de signaux par paquets de données optiques
US8326146B2 (en) 2007-03-15 2012-12-04 Telefonaktiebolaget L M Ericsson (Publ) Communications node for and method of routing optical data packet signals
WO2009015689A1 (fr) * 2007-07-31 2009-02-05 Telefonaktiebolaget Lm Ericsson (Publ) Commutateur batcher banyan tout optique, commutateur batcher, commutateur banyan et gestionnaire de contention
US8787756B2 (en) 2007-07-31 2014-07-22 Telefonaktiebolaget Lm Ericsson (Publ) All optical batcher banyan switch, batcher switch, banyan switch and contention manager

Also Published As

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ES2105652T3 (es) 1997-10-16
NZ261896A (en) 1997-07-27
SG49721A1 (en) 1998-06-15
AU6114094A (en) 1994-09-26
JP3512800B2 (ja) 2004-03-31
AU690097B2 (en) 1998-04-23
WO1994021088A3 (fr) 1994-12-22
CA2157492A1 (fr) 1994-09-15
HK1001009A1 (en) 1998-05-15
CN1119044A (zh) 1996-03-20
US5900956A (en) 1999-05-04
DE69404130D1 (de) 1997-08-14
DE69404130T2 (de) 1997-12-11
CN1067475C (zh) 2001-06-20
KR100321073B1 (ko) 2002-06-20
KR960701570A (ko) 1996-02-24
CA2157492C (fr) 2000-05-09
JPH08507389A (ja) 1996-08-06

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